Light emitting device, surface light source device, display and light flux control member

Abstract

Light from light emitting element enters into a flux control member through a recess on an inner face of the light flux control member, being emitted from an emission control face (outer face). At least so far as light falls within a half-intensity-angular-range, the light satisfies Condition 1 ((θ5/θ1)>1 except for light in the vicinity of a normal direction of the emission control face) and Condition 2 (Value of θ5/θ1>1 gets smaller gradually with increasing of θ1). It is noted that θ1, θ5 are angles made at being inner-incident to the emission control face and at being emitting from the same, respectively. The emission control face has a planar outline shape which is anisotropic around optical axis L, thereby causing value of θ5 /θ1 to have a change depending on direction angle φ around optical axis L, with the result that highly uniform light is supplied to a required anisotropic irradiation range.

1. A light emitting device comprising:
 a light flux control member via which light from a light emitting element is emitted, 
 wherein said light flux control member has a recess and an emission control face, said recess being arranged corresponding to said light emitting element and provides a light input portion for causing light emitted from said light emitting element to be inputted into said light flux control member, and said emission control face causing light inputted into said light flux control member to be outputted after inner propagation, and 
 said emission control face is configured so that a projection image of said emission control face onto an imaginary plane perpendicular to a datum optical axis of said light emitting device provides a planar outline shape anisotropic around said datum optical axis, and so that the following Conditions 1 to 3 are satisfied, 
 Condition 1 is that a relation of (θ5/θ1)>1 is satisfied except for light of directions angularly near to a direction of said datum optical axis, 
 Condition 2 is that the value of θ5/θ1(>1) according to the above Condition 1 gets smaller gradually with increasing of θ1, 
 Condition 3 is that the value of θ5/θ1(>1) according to the above Condition 1 shows dependency on direction around said datum optical axis, 
 where θ1 is an angle made by an inner incident light to said emission control face on inner incidence with respect to a line which passes a position of said inner incidence and is parallel to said datum optical axis of said light emitting device, and θ5 is angle made by said inner incident light with respect to said line on being emitted from said emission control face. 
 
   
   
     2. A light emitting device in accordance with  claim 1 , wherein said planar outline shape has minimum outline portions, which are distant from said datum optical axis by the minimum distance and arranged around said datum optical axis at angular intervals of 90°, and maximum outline portions which are distant from said datum optical axis by the maximum distance and arranged around said datum optical axis and between minimum outline portions adjacent to each other, and further the following Condition 4 is satisfied,
 Condition 4 is that the value of θ5/θ1(>1) according to the above Condition 1 gets greater, under a condition such that θ1 is not changed, as said direction around said datum optical axis gets nearer from a direction corresponding to a minimum outline portion toward another direction corresponding to a maximum outline portion. 
 
   
   
     3. A light emitting device in accordance with  claim 1  or  2 , wherein said light emitting element is accommodated in said recess. 
   
   
     4. A light emitting device in accordance with  claim 1  or  2 , wherein said light of directions angularly near to said direction of said datum optical axis is light falling within a range of ±5° with respect to said direction of said datum optical axis. 
   
   
     5. A light emitting device in accordance with  claim 3 , wherein said light of directions angularly near to said direction of said datum optical axis is light falling within a range of ±5° with respect to said direction of said datum optical axis. 
   
   
     6. A light emitting device in accordance with  claim 3 , wherein a gap is arranged between a surface of said recess and said light emitting element. 
   
   
     7. A light emitting device in accordance with  claim 3 , wherein said light emitting element has a sealing portion consisting of sealing material and a gap is arranged between a surface of said recess and said sealing portion. 
   
   
     8. A light emitting device in accordance with  claim 3 , wherein a surface of said recess is tightly in contact with said light emitting element. 
   
   
     9. A light emitting device in accordance with  claim 3 , wherein said light emitting element has a sealing portion consisting of sealing material and a surface of said recess is tightly in contact with said sealing portion. 
   
   
     10. A light emitting device in accordance with  claim 1  or  2 , wherein said emission control face has a first emission surface near to said datum optical axis and a second emission surface located around said first emission surface, and a point of inflection is provided by a connection portion between said first emission surface and said second emission surface. 
   
   
     11. A light emitting device in accordance with  claim 3 , wherein said emission control face has a first emission surface near to said datum optical axis and a second emission surface located around said first emission surface, and a point of inflection is provided by a connection portion between said first emission surface and said second emission surface. 
   
   
     12. A light emitting device in accordance with  claim 4 , wherein said emission control face has a first emission surface near to said datum optical axis and a second emission surface located around said first emission surface, and a point of inflection is provided by a connection portion between said first emission surface and said second emission surface. 
   
   
     13. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 1  or  2 . 
   
   
     14. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 3 . 
   
   
     15. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 4 . 
   
   
     16. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 5 . 
   
   
     17. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 6 . 
   
   
     18. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 7 . 
   
   
     19. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 8 . 
   
   
     20. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 9 . 
   
   
     21. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 10 . 
   
   
     22. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 11 . 
   
   
     23. A surface light source device comprising at least one light emitting device and a light diffusion member transmitting and diffusing light from said light emitting device, wherein said light emitting device is according to  claim 12 . 
   
   
     24. A light flux control member which allows light from a light emitting element to be inputted thereto and emits direction-controlled light, comprising:
 a recess which is arranged corresponding to said light emitting element and provides a light input portion for causing light emitted from said light emitting element to be inputted into said light flux control member; and 
 an emission control face which causes light inputted into said light flux control member to be outputted after inner propagation, 
 wherein said emission control face is configured so that a projection image of said emission control face onto an imaginary plane perpendicular to an optical axis of said light emitting element provides a planar outline shape anisotropic around said optical axis, and so that the following Conditions 1 to 3 are satisfied, 
 Condition 1 is a relation of (θ5/θ1)>1 is satisfied except for light of directions angularly near to a direction of said optical axis, 
 Condition 2 is that the value of θ5/θ1(>1) according to the above Condition 1 gets smaller gradually with increasing of θ1, 
 Condition 3 is that the value of θ5/θ1(>1) according to the above Condition 1 shows dependency on direction around said optical axis, 
 where θ1 is an angle made by an inner incident light to said emission control face on inner incidence with respect to a line which passes a position of said inner incidence and is parallel to said datum optical axis of said light emitting device, and θ5 is angle made by said inner incident light with respect to said line on being emitted from said emission control face. 
 
   
   
     25. A light flux control member in accordance with  claim 24 , wherein said planar outline shape has minimum outline portions, which are distant from said datum optical axis by the minimum distance and arranged around said datum optical axis at angular intervals of 90°, and maximum outline portions which are distant from said datum optical axis by the maximum distance and arranged around said datum optical axis and between minimum outline portions adjacent to each other, and further the following Condition 4 is satisfied,
 Condition 4 is that the value of θ5/θ1(>1) according to the above Condition 1 gets greater, under a condition such that θ1 is not changed, as said direction around said datum optical axis gets nearer from a direction corresponding to a minimum outline portion toward another direction corresponding to a maximum outline portion. 
 
   
   
     26. A light flux control member in accordance with  claim 24  or  25 , wherein said light emitting element is accommodated in said recess. 
   
   
     27. A light flux control member in accordance with  claim 24  or  25 , wherein said light of directions angularly near to said direction of said optical axis is light falling within a range of ±5° with respect to said direction of said optical axis. 
   
   
     28. A light flux control member in accordance with  claim 26 , wherein said light of directions angularly near to said direction of said optical axis is light falling within a range of ±5° with respect to said direction of said optical axis.